packet-v120.c

   1 /* packet-v120.c
   2  * Routines for v120 frame disassembly
   3  * Bert Driehuis <driehuis@playbeing.org>
   4  *
   5  * $Id: packet-v120.c,v 1.16 2001/01/03 06:55:34 guy Exp $
   6  *
   7  * Ethereal - Network traffic analyzer
   8  * By Gerald Combs <gerald@zing.org>
   9  * Copyright 1998
  10  *
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  25  */
  26
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #ifdef HAVE_SYS_TYPES_H
  32 # include <sys/types.h>
  33 #endif
  34
  35 #include <stdio.h>
  36 #include <glib.h>
  37 #include <string.h>
  38 #include "packet.h"
  39 #include "xdlc.h"
  40
  41 #define FROM_DCE        0x80
  42
  43 static int proto_v120 = -1;
  44 static int hf_v120_address = -1;
  45 static int hf_v120_control = -1;
  46 static int hf_v120_header = -1;
  47
  48 static gint ett_v120 = -1;
  49 static gint ett_v120_address = -1;
  50 static gint ett_v120_control = -1;
  51 static gint ett_v120_header = -1;
  52
  53 static int dissect_v120_header(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree);
  54
  55 static void
  56 dissect_v120(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
  57 {
  58     proto_tree  *v120_tree, *tc, *address_tree;
  59     proto_item  *ti;
  60     int         is_response;
  61     int         addr;
  62     char        info[80];
  63     int         v120len;
  64     guint8      byte0, byte1;
  65     guint16     control;
  66     tvbuff_t    *next_tvb;
  67
  68     CHECK_DISPLAY_AS_DATA(proto_v120, tvb, pinfo, tree);
  69
  70     pinfo->current_proto = "V.120";
  71
  72     if (check_col(pinfo->fd, COL_PROTOCOL))
  73         col_set_str(pinfo->fd, COL_PROTOCOL, "V.120");
  74
  75     byte0 = tvb_get_guint8(tvb, 0);
  76
  77     if(check_col(pinfo->fd, COL_RES_DL_SRC))
  78         col_add_fstr(pinfo->fd, COL_RES_DL_SRC, "0x%02X", byte0);
  79
  80     byte1 = tvb_get_guint8(tvb, 1);
  81
  82     if ((byte0 & 0x01) != 0x00 && (byte1 && 0x01) != 0x01)
  83     {
  84         if (check_col(pinfo->fd, COL_INFO))
  85             col_set_str(pinfo->fd, COL_INFO, "Invalid V.120 frame");
  86         if (tree)
  87             ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, tvb_length(tvb),
  88                                             "Invalid V.120 frame");
  89         return;
  90     }
  91
  92     if (pinfo->pseudo_header->x25.flags & FROM_DCE) {
  93         if(check_col(pinfo->fd, COL_RES_DL_DST))
  94             col_set_str(pinfo->fd, COL_RES_DL_DST, "DTE");
  95         if(check_col(pinfo->fd, COL_RES_DL_SRC))
  96             col_set_str(pinfo->fd, COL_RES_DL_SRC, "DCE");
  97     }
  98     else {
  99         if(check_col(pinfo->fd, COL_RES_DL_DST))
 100             col_set_str(pinfo->fd, COL_RES_DL_DST, "DCE");
 101         if(check_col(pinfo->fd, COL_RES_DL_SRC))
 102             col_set_str(pinfo->fd, COL_RES_DL_SRC, "DTE");
 103     }
 104
 105     if (((pinfo->pseudo_header->x25.flags & FROM_DCE) && byte0 & 0x02) ||
 106        (!(pinfo->pseudo_header->x25.flags & FROM_DCE) && !(byte0 & 0x02)))
 107         is_response = TRUE;
 108     else
 109         is_response = FALSE;
 110
 111     if (tree) {
 112         ti = proto_tree_add_protocol_format(tree, proto_v120, tvb, 0, 0, "V.120");
 113         v120_tree = proto_item_add_subtree(ti, ett_v120);
 114         addr = byte1 << 8 | byte0;
 115         sprintf(info, "LLI: %d C/R: %s",
 116                         ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1),
 117                         byte0 & 0x02 ? "R" : "C");
 118         tc = proto_tree_add_text(v120_tree, tvb,
 119                         0, 2,
 120                         "Address field: %s", info);
 121         address_tree = proto_item_add_subtree(tc, ett_v120_address);
 122         proto_tree_add_text(address_tree, tvb, 0, 2,
 123                     decode_boolean_bitfield(addr, 0x0002, 2*8,
 124                         "Response", "Command"), NULL);
 125         sprintf(info, "LLI: %d", ((byte0 & 0xfc) << 5) | ((byte1 & 0xfe) >> 1));
 126         proto_tree_add_text(address_tree, tvb, 0, 2,
 127                     decode_numeric_bitfield(addr, 0xfefc, 2*8, info));
 128         proto_tree_add_text(address_tree, tvb, 0, 2,
 129                     decode_boolean_bitfield(addr, 0x0001, 2*8,
 130                         "EA0 = 1 (Error)", "EA0 = 0"), NULL);
 131         proto_tree_add_text(address_tree, tvb, 0, 2,
 132                     decode_boolean_bitfield(addr, 0x0100, 2*8,
 133                         "EA1 = 1", "EA1 = 0 (Error)"), NULL);
 134     }
 135     else {
 136         v120_tree = NULL;
 137         ti = NULL;
 138     }
 139     control = dissect_xdlc_control(tvb, 2, pinfo, v120_tree, hf_v120_control,
 140             ett_v120_control, is_response, TRUE);
 141     if (tree) {
 142         v120len = 2 + XDLC_CONTROL_LEN(control, TRUE);
 143         if (tvb_bytes_exist(tvb, v120len, 1))
 144                 v120len += dissect_v120_header(tvb, v120len, pinfo, v120_tree);
 145         proto_item_set_len(ti, v120len);
 146         next_tvb = tvb_new_subset(tvb, v120len, -1, -1);
 147         dissect_data(next_tvb, 0, pinfo, v120_tree);
 148     }
 149 }
 150
 151 static int
 152 dissect_v120_header(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree)
 153 {
 154         char info[80];
 155         int header_len, nbits;
 156         int header;
 157         proto_tree *h_tree, *tc;
 158         guint8  byte0;
 159
 160         byte0 = tvb_get_guint8(tvb, offset);
 161
 162         if (byte0 & 0x80) {
 163                 header_len = 1;
 164                 header = byte0;
 165         } else {
 166                 header_len = 2;
 167                 header = byte0 | tvb_get_guint8(tvb, offset + 1) << 8;
 168         }
 169         nbits = header_len * 8;
 170         sprintf(info, "Header: B: %d F: %d", byte0 & 0x02 ? 1:0,
 171                         byte0 & 0x01 ? 1:0);
 172         tc = proto_tree_add_text(tree, tvb,
 173                         offset, header_len,
 174                         "Header octet: %s (0x%02X)", info, byte0);
 175         h_tree = proto_item_add_subtree(tc, ett_v120_header);
 176         proto_tree_add_text(h_tree, tvb, offset, header_len,
 177                     decode_boolean_bitfield(header, 0x80, nbits,
 178                         "No extension octet", "Extension octet follows"), NULL);
 179         proto_tree_add_text(h_tree, tvb, offset, header_len,
 180                     decode_boolean_bitfield(header, 0x40, nbits,
 181                         "Break condition", "No break condition"), NULL);
 182         sprintf(info, "Error control C1/C2: %d", (header & 0x0c) >> 2);
 183         proto_tree_add_text(h_tree, tvb, offset, header_len,
 184                     decode_numeric_bitfield(header, 0x0c, nbits, info));
 185         proto_tree_add_text(h_tree, tvb, offset, header_len,
 186                     decode_boolean_bitfield(header, 0x02, nbits,
 187                         "Segmentation bit B", "No segmentation bit B"), NULL);
 188         proto_tree_add_text(h_tree, tvb, offset, header_len,
 189                     decode_boolean_bitfield(header, 0x01, nbits,
 190                         "Segmentation bit F", "No segmentation bit F"), NULL);
 191         if (header_len == 2) {
 192                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 193                     decode_boolean_bitfield(header, 0x8000, nbits,
 194                         "E", "E bit not set (Error)"), NULL);
 195                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 196                     decode_boolean_bitfield(header, 0x4000, nbits,
 197                         "DR", "No DR"), NULL);
 198                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 199                     decode_boolean_bitfield(header, 0x2000, nbits,
 200                         "SR", "No SR"), NULL);
 201                 proto_tree_add_text(h_tree, tvb, offset, header_len,
 202                     decode_boolean_bitfield(header, 0x1000, nbits,
 203                         "RR", "No RR"), NULL);
 204         }
 205         return header_len;
 206 }
 207
 208 void
 209 proto_register_v120(void)
 210 {
 211     static hf_register_info hf[] = {
 212         { &hf_v120_address,
 213           { "Link Address", "v120.address", FT_UINT16, BASE_HEX, NULL,
 214                   0x0, "" }},
 215         { &hf_v120_control,
 216           { "Control Field", "v120.control", FT_UINT16, BASE_HEX, NULL, 0x0,
 217                 "" }},
 218         { &hf_v120_header,
 219           { "Header Field", "v120.header", FT_STRING, BASE_NONE, NULL, 0x0,
 220                 "" }},
 221     };
 222     static gint *ett[] = {
 223         &ett_v120,
 224         &ett_v120_address,
 225         &ett_v120_control,
 226         &ett_v120_header,
 227     };
 228
 229     proto_v120 = proto_register_protocol("Async data over ISDN (V.120)",
 230                                          "V.120", "v120");
 231     proto_register_field_array (proto_v120, hf, array_length(hf));
 232     proto_register_subtree_array(ett, array_length(ett));
 233 }
 234
 235 void
 236 proto_reg_handoff_v120(void)
 237 {
 238         dissector_add("wtap_encap", WTAP_ENCAP_V120, dissect_v120);
 239 }